5. Garlic being sold as organic was found to contain pesticide and was removed from the market.
- c residues

6. A well-known journalist uncovered secret documents relating to high levels of lead in household water supplies.
- a investigative

7. Scientists believe that procreation from a diverse _____ creates stronger, taller and more intelligent offspring.
- c gene pool

8. When temperatures drop below freezing, frogs burrow down into the soil to survive.
- d below

19. On cold nights, gardeners cover plants with straw to protect them from being damaged by _____.
- b frost

20. Orchids grow better in _____ atmosphere as they require 40–70 per cent moisture in the air.
- b a humid